Method and apparatus for chemical vapor deposition of polysilicon

• US 6,284,312 B1
• Filed: 02/18/2000
• Issued: 09/04/2001
• Est. Priority Date: 02/19/1999
• Status: Expired due to Fees

• Current Assignee: GTAT Corporation (ON Semiconductor Corporation)
• Original Assignee: GT Equipment Technologies, Inc. (ON Semiconductor Corporation)
• Inventors: Gupta, Kedar Prasad, Jafri, Ijaz Hussain, Prasad, Vishwanath, Chandra, Mohan, Talbott, Jonathan A.
• Primary Examiner(s): Beck, Shrive P.
• Assistant Examiner(s): BARR, MICHAEL E
• Application Number:
  US09/507,711
• Time in Patent Office: 564 Days
• Field of Search: 427/237, 427/255.27, 427/255.28, 427/255.393, 427/255.18, 427/255.17, 427/314, 423/348, 423/349, 423/350
• US Class Current: 427/237
• CPC Class Codes: C01B 33/027 by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 16/24 Deposition of silicon only

Abstract

A method and apparatus, and product by process, for the production of bulk polysilicon by broad area chemical vapor deposition, consisting of a quartz envelope and base plate forming a reactor enclosure, with external radiant heaters providing the heat source. A thin wall, edge-defined film fed growth (EFG) silicon tube section is used as the deposition casing and reaction chamber wall. The tube is capped at the top and sealed to the base plate to form the reaction chamber. External heaters radiate heat through the quartz enclosure to heat the tube wall to deposition temperature. A through flow of process gas is introduced to initiate the deposition. A uniform wide surface area deposit occurs on the inside surface of the tube, causing the diameter to become increasingly smaller as the yield accumulates. In a two tube reactor, a smaller core tube is uniformly spaced and supported inside the outer tube for full flow of process gas around the core tube so that deposition occurs on both the outside and inside surface of the core tube. The outer tube may be configured for preheating by a flow of electrical current from the base plate to the cover plate.

Claims

1. A method for production of bulk polysilicon by chemical vapor deposition comprising the steps of:

using a quartz envelope on a base plate with an inlet port and an outlet port, each said port communicating with the interior of said envelope,

vertically emplacing within said envelope on said base plate an enclosed tubular silicon casing positioned so as to be communicating with said inlet port and said outlet port,

raising to and maintaining the interior surface of said casing at the deposition temperature of a select combination of carrier gas and silicon reactant material using a heat source comprising at least a radiant heat source external of said quartz envelope,

flowing said carrier gas ladened with said silicon reactant material through said inlet port into said enclosure,

conducting within said tubular casing a CVD process utilizing said combination of carrier gas and silicon reactant material such that a bulk polysilicon layer is deposited upon the interior wall of said tubular casing,

flowing gaseous byproducts of said CVD process out of said enclosure through said outlet port,

removing as a bulk polysilicon product from said quartz envelope said tubular casing with said bulk polysilicon layer.

2. A method for production of bulk polysilicon by chemical vapor deposition comprising the steps of:

using a cold wall chemical vapor deposition reactor comprising a quartz envelope attachable to a base plate so as to form a closed quartz enclosure, a process gas inlet and a process gas outlet in said base plate communicating with said enclosure, and outer tube support system on said base plate within said closed quartz enclosure enclosing said gas inlet port and said gas outlet port, and a cover plate,

vertically emplacing within said enclosure on said tube support system an outer tube,

capping the upper end of said outer tube with said cover plate so as to form within said enclosure a closed reaction chamber bounded by said base plate and said tube support system and the interior surface of said outer tube and said cover plate,

applying radiant heat to said closed quartz enclosure sufficient for raising to and maintaining the interior surface of said outer tube at the deposition temperature of a select combination of carrier gas and silicon reactant material,

flowing said carrier gas ladened with said silicon reactant material through said process gas inlet port into said primary reaction chamber,

conducting within said closed reaction chamber a CVD process utilizing said combination of carrier gas and silicon reactant material such that a bulk polysilicon layer is deposited upon the interior surface of said outer tube and said cover plate,

flowing gaseous byproducts of said CVD process out through said process gas outlet port, and

removing as a bulk polysilicon product from said quartz envelope said outer tube with said bulk polysilicon layer.

3. A method for producing polysilicon according to claim 2, said reactor further comprising a blanket zone between said quartz envelope and said reaction chamber, and a blanket gas port in said base plate communicating with said blanket zone, said method further comprising the steps of:

admitting a blanket gas through said blanket gas port into said blanket gas zone,

maintaining positive pressure in said blanket gas zone with respect to said primary reaction chamber during said CVD process.

4. A method for producing polysilicon according to claim 3, said carrier gas and said blanket gas being hydrogen.

5. A method for producing polysilicon according to claim 3, said carrier gas and said blanket gas being the same gas.

6. A method for producing polysilicon according to claim 2, said carrier gas being hydrogen, said silicon reactant material being silane.

7. A method for producing polysilicon according to claim 2, said carrier gas being hydrogen, said silicon reactant material being a chlorosilane.

8. A method for producing polysilicon according to claim 2, said carrier gas being an inert gas.

9. A method for producing polysilicon according to claim 2, said means for applying heat comprising using an external radiant heater assembly surrounding said quartz envelope.

10. A method for production of bulk polysilicon according to claim 2, said reactor further comprising a core tube support system on said base plate, said core tube support system being of smaller diameter and centered within said outer tube support system and ventilated for through flow of gas, said method comprising the further steps:

vertically emplacing within said reactor on said core tube support system a silicon core tube, said core tube being of smaller diameter than said outer tube and open at both ends,

applying sufficient heat to said silicon core tube so as to raise to and maintain the surfaces of said core tube at the deposition temperature of said select combination of carrier gas and silicon reactant material during said CVD process,

removing as a bulk polysilicon product from said quartz envelope said core tube with a said bulk polysilicon layer deposited on both inner and outer surfaces thereof.

11. A method for production of bulk polysilicon by chemical vapor deposition comprising the steps of:

using a quartz envelope on a base plate with an inlet port and and outlet port, each said port communication with the interior of said envelope,

vertically emplacing within said envelope on said base plate an open ended core tube,

vertically emplacing within said envelope on said base plate an enclosed tubular silicon casing positioned so as to encompass and not contact said core tube and to be communicating with said inlet port and said outlet port,

raising to and maintaining the interior surface of said casing and said core tube at the deposition temperature of a select combination of carrier gas and silicon reactant material using a heat source comprising a radiant heat source external of said quartz envelope,

flowing said carrier gas ladened with said silicon reactant material through said inlet port into said enclosure,

conducting within said tubular casing a CVD process utilizing said combination of carrier gas and silicon reactant material such that a bulk polysilicon layer is deposited upon the interior wall of said tubular casing and upon the interior and exterior walls of said core tube,

flowing gaseous byproducts of said CVD process out of said enclosure through said outlet port,

removing as a bulk polysilicon product from said quartz envelope said core tube and tubular casing with said bulk polysilicon layers.

12. A method for production of bulk polysilicon by chemical vapor deposition comprising the steps of:

using a cold wall chemical vapor deposition reactor comprising a quartz envelope attachable to a base plate so as to form a closed quartz enclosure, a process gas inlet and a process gas outlet in said base plate communicating with said enclosure, an outer tube support system on said base plate within said closed quartz enclosure enclosing said gas inlet port and said gas outlet port, and a cover plate, said reactor further comprising a core tube support system on said base plate, said core tube support system being of smaller diameter and dcentered within said outer tube support system and ventilated for through flow gas,

vertically emplacing within said enclosure on said core tube support system a silicon core tube, said core tube being of smaller diameter than said outer tube and open at both ends,

vertically emplacing within said enclosure on said tube support system an outer tube,

capping the upper end of said outer tube with said cover plate so as to form within said enclosure a closed reaction chamber bounded by said bas plate and said tube support system and the interior surface of said outer tube and said cover plate,

applying radiant heat to said closed quartz enclosure sufficient for raising to and maintaining the interior surfaceds of said outer tube and said core tube at the deposition temperature of a select combination of carrier gas and silicon reactant material,

flowing said carrier gas ladened with said silicon reactant material through said process gas inlet port into said primary reaction chamber,

conducting within said closed reacton chamber a CVD process utilizing said combination of carrier gas and silicon reactant material such that a bulk polysilicon layer is deposited upon the interior surface of said outer tube and said cover plate,

flowing the gaseous byproducts of said CVD process out through said process gas outlet port, and

removing as a bulk polysilicon product from said quartz envelope said outer tube and said core tube with said bulk polysilicon layers.

13. A method for producing polysilicon according to claim 12, said reactor further comprising a blanket zone between said quartz envelope and said reaction chamber, and a blanket gas port in said base plate communicating with said blanket zone, said method further comprising the steps of:

admitting a blanket gas through said blanket gas port into said blanket gas zone,

maintaining positive pressure in said blanket gas zone with respect to said primary reaction chamber during said CVD process.

14. A method for producing polysilicon according to claim 13, said carrier gas and said blanket gas being hydrogen.

15. A method for producing polysilicon according to claim 13, said carrier gas and said blanket gas being the same gas.

16. A method for producing polysilicon according to claim 12, said carrier gas being hydrogen, said silicon reactant material being silane.

17. A method for producing polysilicon according to claim 12, said carrier gas being hydrogen, said silicon reactant material being a chlorosilane.

18. A method for producing polysilicon according to claim 12, said carrier gas being an inert gas.

19. A method for producing polysilicon according to claim 12, said means for applying radiant heat comprising using an external radiant heater assembly surrounding said quartz envelope.